Electrical Transmission and Distribution System

If you want to be an electrical engineer then knowing about the single line diagram of electrical transmission and distribution system and it’s really important in your practical life. Sometimes it can be a question while you are in an interview board. In this post, I am going to discuss all the basic for this topic.

This figure is showing the layout for a typical AC power transmission and distribution system by a single line diagram.

Generation Station:

This is the very first sector for everything. And this is where we produce electricity. There are several power plant can be used to produce electricity like GAS Fuel Power Station, Nuclear Power Station, and others. In this figure that I provided, there is a part that called Generating Station where we can produce electric power by three-phase alternator operating in parallel.

The most common generating voltage is 11KV. But sometime 3.3KV or 6.6KV are used for industrial captive power generation. Now come to transmission. For economy in the transmission of electric power, the generation voltage is stepped up to 132KV or above by a three-phase power transformer. This type of transformer called a step-up transformer.

Primary Transmission:

The steeped up electric power 132KV or above is transmitted by three phases, three wire overhead line system to the outskirts of the city. This forms the primary transmission.

Secondary Transmission:

Primary Distribution:

Form this parts all industrial consumer those who need bulk power and they can connect with this Primary Distribution parts. But they will need special permission from the government for a special occasion.

Secondary Distribution:

From this sector, all 11KV consumer and 220V single line consumer will get the power. For 220V distribution system, a transformer 3 phase or single phase will be used for step down from 11KV/440V or 220V.